Ramp-Rate Methodology
Mark Rothleder
Principal Market Developer
MRTU Market Simulation Pricing Briefing
September 19, 2008
Ramp-Rate Principles
 4 ramp-rate segments can be modeled
 In addition to the ramp-rate segments up to 2-Forbidden
Regions can be modeled
 An aggregate ramp-rate curve made up of the
operational ramp-rate and Forbidden Operating Regions
is created
 Aggregate ramp-rate curve will still be used even if
Forbidden Region is not enforced
Slide 2
Ramp-Rate Issues
 For past 6 months ability to accommodate varying ramprates has improved
 In cases where large ramp-rates changes exist from one
operating range to another we observe significant impact
on performance
 Large Ramp-Rate changes appear to being used to
model combined cycle
Slide 3
Ramp-Rate Proposed Solution
 Limit ramp-rate changes where ramp-rate change from
one operating range to next operating range to a 10:1
change
 CAISO will internally adjust ramp-rate to achieve a 10:1
ratio if submitted ramp-rate is not achieved
 A Normal Card can be used to hold a resource at a
required MW until resource is able to ramp at the
adjusted ramp rate
Slide 4
Ramp-Rate Example
Resource has for ramp-rate segments
•0-10 MW at 5 MW/min
•10-20 MW at .4 Mw/min
•20-100 MW at 5 Mw/min
•100-150 Mw at 10 Mw/min
•Forbidden Region between 30-90 MW with Transit Time = 60 minutes
Operating
RampForbidden Aggregate
RampMaximum Ok/Not Corrected
Range
Rate
Region
Effective
Rate
Change
Ok
(Mw)
(Mw/Min)
Transit
RampChange
(10:1)x
Time
Rate
(Upward
min
(min)
Direction) ramp-rate
0
5
5
Ok
5
10
.4
.4
4.6
4.0
Not.5
Ok
20
5
5
4.6
4.0
Not5
Ok
30
For.Reg.
60
1
4
10.0
Ok
1
90
For.Reg.
5
4
10.0
Ok
5
100
10
10
5
50.0
Ok
10
150
-
Slide 5